TEHRAN, Iran (AP) — Gunmen killed three border guards and wounded one other person Thursday in restive southeastern Iran, state-run media reported.

IRNA news agency reported that gunmen in a car opened fire on a border regiment vehicle in Mirjaveh county in southeast Sistan and Baluchistan province, near the Pakistani border, killing two soldiers and an officer. A civilian was wounded.

IRNA said the militant group Jaish al-Adl, which allegedly seeks greater rights for the ethnic Baluch minority, claimed responsibility for the attack.

In April, in two separate clashes in the province, at least 22 Iranian policemen died.

The province, bordering Afghanistan and Pakistan, has been the site of occasional deadly clashes involving militant groups, armed drug smugglers, and Iranian security forces. In December, militants killed nearly a dozen police officers in an attack on a police station in the province.

Sistan and Baluchistan province is one of the least developed parts of Iran. Relations between the predominantly Sunni Muslim residents of the region and Iran’s Shiite theocracy have long been strained.